Islamabad , Pakistan -LRB- CNN -RRB- -- A suspected U.S. drone strike in Pakistan 's tribal region killed six suspected militants on Wednesday , intelligence officials told CNN .

Two Pakistani intelligence officials said the suspected drone fired two missiles on a militant hideout in South Waziristan , one of the seven districts of Pakistan 's volatile tribal region bordering Afghanistan .

The intelligence officials asked not to be named because they are not authorized to speak to the media .

Wednesday 's strike is the first since March 17 , when a drone strike in North Waziristan killed 44 people -- most of them civilians , two Pakistani sources said .

Such strikes have inflamed tensions between Pakistan and the United States . Pakistan has formally asked the United States for an apology for the March 17 strike .

The United States does not officially acknowledge the Central Intelligence Agency 's secret drone program that targets al Qaeda militants , but it is the only country operating in the region with the capability to carry out such strikes .

A senior Pakistani intelligence official told CNN drone strikes carried out by Americans -- once widely believed to have the tacit approval and cooperation of Pakistani intelligence -- are now carried out autonomously by the CIA .

`` It 's unilateral action , '' he said .

The official expressed dismay after Wednesday 's strike .

`` What is this ? A message -LRB- from the Americans -RRB- that it 's business as usual , irrespective of what we ask of you ? If it is , it 's a crude way of getting your message across , '' he said .

The official added that Pakistan had asked the United States to curtail its drone strikes in remote tribal areas .

`` We are not necessarily saying stop . What we are saying is irrespective of tactical games , this is not useful in the long run , '' he said . `` We need a relook and to not be too trigger happy and be selective . ''

The drone strike came just two days after Pakistan 's intelligence chief , Lt. Gen. Ahmed Shuja Pasha , met with CIA Director Leon Panetta at CIA headquarters to voice his government 's complaints about CIA activities in his country .

In addition to the aerial attacks , the Pakistanis are angered by what they say is the lack of transparency about the number of CIA operatives and the extent of American intelligence activities within their country .

Although the U.S.-Pakistani relationship has been on rocky ground for some time , It came to a head when CIA contractor

Raymond Davis was arrested after killing two Pakistani men in Lahore . Although the United States said Davis was a security officer assigned to protect CIA officers , the Pakistanis maintained he was actually a spy whom they had been unaware of prior to the shooting incident .

Pakistani officials insisted this week that the United States give them details about other CIA contractors in the country .

A U.S. official who is not authorized to speak for attribution said there is a `` desire to expand cooperation across a wide range of joint activities with the Pakistanis , '' but would not elaborate on what steps the United States is taking .

The official would not talk specifically about the drone strikes , but did say Panetta made it clear in his meeting with Pasha that `` his fundamental responsibility is to protect the American people and there will not be a halt to operations that support that objective . ''

The official said the United States has `` an obligation '' to protect American troops fighting militants on the Afghanistan side of the border .

`` If on the Pakistani side of the border there are bad people planning bad things against our troops , the U.S. would be remiss if it did n't take steps to thwart those activities , '' said the official .

The official raised the questions : `` What do the Pakistani 's expect ? If foot soldiers are carrying bombs across the border , do they expect the U.S. to sit idly by ? ''

The official said if the Pakistanis do n't take action against extremists operating in their territory , than the United States will .

`` Pakistan needs to talk more about what they 're doing and less about what they think the U.S. is doing , '' the official said .

Based on a count by CNN 's Islamabad bureau , Wednesday 's suspected drone strike was the 19th this year , compared with 111 in all of 2010 .

CNN 's Nick Paton Walsh contributed to this report .

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NEW : `` Do they expect the U.S. to sit idly by ? '' a U.S. official asks of the Pakistanis

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A drone fired two missiles on a militant hideout , two intelligence officials say

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Source : Pakistan has asked the United States to curtail drone strikes in remote tribal areas

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`` This is not useful in the long run , '' the senior Pakistani intelligence official says